FITCHBURG — U.S. Department of Justice Federal Bureau of Alcohol, Tobacco and Firearms and Explosives Agent Scott L. Heagney alleges Mayor Lisa A. Wong withdrew her nomination Tuesday to name him the next police chief over an anonymous "poison pen" letter before she even tried to find out if it was factual.

Mr. Heagney was Ms. Wong's top pick to replace Chief Robert A. DeMoura, who is leaving March 31.

Until Monday, Mr. Heagney said everything was going fine and he had already started discussions with the police union and talked with the chief.

He was to drive from his home in Rochester, N.Y., Wednesday night for his confirmation by City Council Thursday evening, he said.

Then, he received a call Monday from the city's human resources director, Bernard Stephens, about an anonymous letter from Attleboro where his brother is police chief, his deceased father worked as captain and he started his law enforcement career as a patrolman.

Mr. Heagney said his brother has made some enemies cleaning up corruption since taking the chief's position and believes the letter was written in retaliation.

The letter is disparaging and full of inaccuracies about his past, Mr. Heagney said.

"This is all about the anonymous letter," he said.

Ms. Wong told councilors via email Tuesday of her decision to withdraw her nomination and said she had suspended contract negotiations and completion of his background check and would re-advertise the position.

Ms. Wong would not say why she made the decision, but told a reporter it had nothing to do with the letter. She did not immediately return calls for comment Wednesday night.

Mr. Heagney said he feels the mayor should have stood behind him and completed the background check that would have proved the allegations in the letter were false.

"I feel like the rug was pulled out from underneath me," he said. "She said it wasn't about the letter, but that is a baldfaced lie. ... I have never been this mistreated in my professional career by any official."

Also included in the letter was information about a 1988 court case in which Mr. Heagney was charged with physical abuse of his then girlfriend. He said the case went to trial and he was found not guilty.

However, Ms. Wong indicated to him during their phone conversations Monday she was upset he did not disclose the incident, he said.